Rubber-reinforcing glass fiber product

ABSTRACT

A treating agent comprises a nitrile group-containing highly saturated polymer rubber latex (A) having an iodine value of 120 or less, a rubber latex (B) other than the highly saturated polymer rubber latex, and a water-soluble resorcinol/formaldehyde condensate in amounts of 15 to 80%, 5 to 70% and 2 to 15%, all by weight in terms of solids, respectively. A rubber-reinforcing fiber product is coated with the treating agent. A rubber article such as a toothed belt, a tire and the like is made using this rubber-reinforcing fiber product. The glass fiber product coated with the treating agent may be further coated with a halogen-containing polymer-based adhesive as a secondary treating agent. Thus, the treating agent exhibits a large bonding force between the reinforcing fiber product and a matrix. Even if the rubber article is repeatedly subjected to a flexing stress, the strength thereof cannot be reduced. A peel-off cannot occurs between the reinforcing fiber product and the rubber matrix. Moreover, the rubber article has sufficient heat and water resistances.

TECHNICAL FIELD

The present invention relates to a glass fiber coating composition, arubber-reinforcing glass fiber product coated with the coatingcomposition, and a rubber article such as a rubber belt, a tire and thelike, formed using the glass fiber product as a reinforcing material,and a process for treating the glass fiber.

BACKGROUND ART

Reinforcing fibers such as a glass fiber have been conventionally widelyused as a reinforcing material for rubber articles such as a rubberbelt, a tire and the like.

The rubber articles such as the rubber belt may be repeatedly subjectedto a flexing stress to cause a flex fatigue, resulting in a reducedperformance, a peel-off between the reinforcing material and a rubbermatrix and a wearing of the reinforcing fiber. Further, the strength isliable to be reduced. Such phenomena tend to be particularly acceleratedby a heat and water. In order to prevent a peel-off due to such a flexfatigue and to provide a sufficient reinforcing effect, it is necessaryto increase the conformity and adhesion between the reinforcing fiberand the rubber and to provide the rubber article with heat and waterresistances. For this purpose, various treating agents may be appliedonto the surface of the reinforcing fiber.

For example, in Japanese Patent Application Laid-open No. 221433/89, atreating agent has been proposed which employs, in combination, awater-soluble resorcinol-formaldehyde condensate, avinylpyridine/butadiene/styrene terpolymer latex, a dicarboxylatedbutadiene/styrene copolymer latex and a chlorosulfonated polyethylenelatex.

The use of such a treating agent makes it possible to satisfy theadhesion between the reinforcing fiber and the rubber matrix and theheat and flex resistances of the treating agent itself to a certainextent, but is accompanied by a disadvantage that when a reinforcingfiber coated with such treating agent is used, sufficiently satisfactoryheat, water and flex resistances cannot be obtained because of ainsufficient water resistance of the treating agent itself and hence, itis difficult to provide an excellent rubber article.

The present inventors have previously invented and proposed arubber-reinforcing glass fiber cord coated with a composition consistingessentially of a water-soluble resorcinol/formaldehyde condensate havingan improved adhesive strength to a heat-resistant rubber, and a nitrilegroup-containing highly saturated polymer rubber having an iodine valueof 120 or less (see Japanese Patent Application Laid-open No.270877/88). This invention and proposal have been accomplished byfinding that the strength of a rubber film and the adhesive strength tothe matrix rubber are enhanced by using a nitrile group-containinghighly saturated polymer rubber having an iodine value of 120 or less,preferably 0 to 100.

Even in the above-described invention by the present inventors, a scopefor improvement for water and flex resistances has been left.

It is an object of the present invention to provide a reinforcing fiberproduct in which the disadvantages associated with the prior art areovercome, and which exhibits a large bonding force between a reinforcingfiber and a rubber matrix, and which cannot be reduced in strength, evenif it is repeatedly subjected to a flexing stress, and which cannotproduce a peel-off between the reinforcing fiber product and the rubbermatrix and moreover, has sufficient heat and water resistances.

DISCLOSURE OF THE INVENTION

The present invention embraces following aspects (1) to (7):

(1) A glass fiber coating composition comprising a nitrilegroup-containing highly saturated polymer rubber latex (A) having aniodine value of 120 or less, a rubber latex (B) other than the highlysaturated polymer rubber latex, and a water-solubleresorcinol/formaldehyde condensate in amounts of 15 to 80%, 5 to 70% and2 to 15%, all by weight in terms of solids, respectively.

(2) A rubber-reinforcing glass fiber product which is coated with atreating agent comprising a nitrile group-containing highly saturatedpolymer rubber latex (A) having an iodine value of 120 or less, a rubberlatex (B) other than the highly saturated polymer rubber latex, and awater-soluble resorcinol/formaldehyde condensate in amounts of 15 to80%, 5 to 70% and 2 to 15%, all by weight in terms of solids,respectively.

(3) A rubber-reinforcing glass fiber product, which is coated with atreating agent comprising a nitrile group-containing highly saturatedpolymer rubber latex (A) having an iodine value of 320 or less, a rubberlatex (B) other than the highly saturated polymer rubber latex, and awater-soluble resorcinol/formaldehyde condensate in amounts of 15 to80%, 5 to 70% and 2 to 15%, all by weight in terms of solids,respectively, and which is further coated with a halogen-containingpolymer-based adhesive solution.

(4) A rubber article made using a glass fiber product which is coatedwith a treating agent comprising a nitrile group-containing highlysaturated polymer rubber latex (A) having an iodine value of 120 orless, a rubber latex (B) other than the highly saturated polymer rubberlatex, and a water-soluble resorcinol/formaldehyde condensate in amountsof 15 to 80%, 5 to 70% and 2 to 15%, all by weight in terms of solids,respectively.

(5) A rubber article made using a glass fiber product which is coatedwith a treating agent comprising a nitrile group-containing containinghighly saturated polymer rubber latex (A) having an iodine value of 120or less, a rubber latex (B) other than the highly saturated polymerrubber latex, and a water-soluble resorcinol/formaldehyde condensate inamounts of 15 to 80%, 5 to 70% and 2 to 15%, all by weight in terms ofsolids, respectively, and which is further coated with ahalogen-containing polymer-based adhesive solution.

(6) A process for coating a rubber-reinforcing glass fiber product,comprising the step of coating the rubber-reinforcing glass fiberproduct with a treating agent which comprises a nitrile group-containinghighly saturated polymer rubber latex (A) having an iodine value of 120or less, a rubber latex (B) other than the highly saturated polymerrubber latex, and a water-soluble resorcinol/formaldehyde condensate inamounts of 15 to 80%, 5 to 70% and 2 to 15%, all by weight in terms ofsolids, respectively.

(7) A process for coating a rubber-reinforcing glass fiber product,comprising the steps of coating the rubber-reinforcing glass fiberproduct with a treating agent which comprises a nitrile group-containinghighly saturated polymer rubber latex (A) having an iodine value of 120or less, a rubber latex (B) other than the highly saturated polymerrubber latex, and a water-soluble resorcinol/formaldehyde condensate inamounts of 15 to 80%, 5 to 70% and 2 to 15%, all by weight in terms ofsolids, respectively, and coating the resulting product with ahalogen-containing polymer-based adhesive solution.

The present invention will now be described in further detail.

The nitrile group-containing highly saturated polymer rubber latex (A)used in the present invention is required to have an iodine value of 120or less, preferably, in a range of 0 to 100 from the viewpoints ofstrength of a rubber film and adhesive strength to the matrix rubber. Apreferred example of the latex which may be used is Zetpole Latex 2020(which has an iodine value of 28, and which is made by Nippon Zeon Co.,Corp.). It should be noted that the iodine value was determinedaccording to JIS K0070. The nitrile group-containing highly saturatedpolymer rubbers (A) includes a rubber made by hydrogenating a conjugateddiene unit moiety of an unsaturated nitrile/conjugated diene copolymerrubbers; an unsaturated nitrile/conjugated diene/ethylenicallyunsaturated monomer tridimensional copolymer rubber and the derivativesmade by hydrogenation thereof; an unsaturated nitrile/ethylenicallyunsaturated monomer based copolymer rubber. The unsaturatednitrile/ethylenically unsaturated monomer based copolymer rubber may bea rubber made by substituting a portion of the unsaturated monomer by anon-conjugated diene such as vinyl-norbornene, dicyclopentadiene, and1,4-hexadiene, and then subjecting the resulting substance to acopolymerization.

Specified examples of these nitrile group-containing highly saturatedpolymer rubbers (A) are those made by hydrogenating abutadiene/acrylonitrile copolymer rubber, anisoprene/butadiene/acrylonitrile copolymer rubber, anisoprene/acrylonitrile copolymer rubber; abutadiene/methylacrylate/acrylonitrile copolymer rubber, abutadiene/acrylic acid/acrylonitrile copolymer rubber, etc., and thederivatives made by hydrogenation thereof; abutadiene/ethylene/acrylonitrile copolymer rubber, abutylacrylate/ethoxyethyleacrylate/vinylchloroacetate/acrylonitrilecopolymer rubber, abutylacrylate/ethoxyethylacrylate/vinylnorbornene/acrylonitrilecopolymer rubber, and the like. They may be produced using a usualpolymerizing technique and a usual hydrogenating process.

Preferred examples of the rubber latices (B) other than the highlysaturated rubber latex, which may be used, are a butadiene/styrenecopolymer latex, a dicarboxylated butadiene/styrene copolymer latex, avinylpyridine/butadiene/styrene terpolymer latex, a chlorosulfonatedpolyethylene latex, an acrylonitrile/butadiene copolymer latex having aniodine value of 200 or more, and the like. If a mixture of avinylpyridine/butadiene/styrene terpolymer latex and a chlorosulfonatedpolyethylene latex, among them, is used, a particularly appropriateeffect can be provided. Preferred examples of the latex which may beused are J9040 (which is a trade name and made by Sumitomo Norgatta Co.,Corp.), Nipol LX 110 (which is a trade name and made by Nippon Zeon Co.,Corp.), and the like.

Particularly suitable examples of the dicarboxylated butadiene/styrenecopolymer latex are those containing 20 to 80% by weight of butadiene, 5to 70% by weight of styrene, and 1 to 10% by weight of an ethylenicallyunsaturated dicarboxylic acid, including Nipol 2570X5 (which is a tradename and is made by Nippon Zeon Co., Corp.), JSR 0668 (which is a tradename and is made by Nippon Gousei Gomu K.K.) and the like.

The vinylpyridine/butadiene/styrene terpolymer latex which can be usedinclude a large number of such terpolymers well known to those skilledin the art. For example, a terpolymer containing vinylpyridine,butadiene and styrene in a proportion of polymerization of 10-20: 60-80:10-20 is particularly preferred, such as Nipol 2518FS (which is a tradename and is made by Nippon Zeon Co., Corp.), Pyratex (which is a tradename and is made by Sumitomo Norgatta Co., Corp.) and the like.

Particularly suitable examples of the chlorosulfonated polyethylenelatex are those containing 25 to 43% by weight of chlorine and 1.0 to1.5% by weight of sulfur, such as Esprene (which is a trade name and ismade by Sumitomo Chemical Co., Ltd.).

Particularly suitable examples of the acrylonitrile/butadiene copolymerlatex having an iodine value of 200 or more are those having abound-acrylonitrile content of 36 to 43% by weight, such Nipol 1561(which is a trade name and is made by Nippon Zeon Co., Corp.), and thelike.

Suitable examples of the water-soluble resorcinol-formaldehydecondensate (which will be referred to as RF hereinafter) which may beused in the present invention are resorcinol-based water-solubleaddition condensate produced from a reaction of resorcinol andformaldehyde in the presence of an alkaline catalyst such as alkalihydroxide and an amine. Particularly, it is desirable to use acondensate produced from a reaction of resorcinol (R) and formaldehyde(F) at a reaction mole ratio R/F of 1:0.53-3.

According to the present invention, a nitrile group-containing highlysaturated polymer rubber latex (A) having an iodine value of 120 orless, a rubber latex (B) and a water-soluble resorcinol/formaldehydecondensate are mixed homogeneously in amounts of 15 to 80%, 5 to 70% and2 to 15% by weight in terms of solids, respectively. A more preferableproportion of incorporation is such that the amount of the component (A)is of 30 to 70% by weight; the amount of the component (B) is of 20 to60% by weight, and the amount of the condensate is of 3 to 12% byweight. If the proportion of the nitrile group-containing highlysaturated polymer rubber latex in the treating agent is less than 15% byweight and exceeds 80% by weight, the resulting treating agent will haveunimproved heat-, water- and flex-resistances. If the amount of RFexceeds 12% by weight, a coating of the resulting treating agent of thepresent invention will be hardened and hence, sufficient flex-fatigueresistance cannot be obtained. If the amount of RF is less than 3% byweight, a sufficient adhesion between the reinforcing fiber and therubber matrix cannot be obtained. If the amount of the rubber latex (B)exceeds 70% by weight, a sufficient heat and flex resistances cannot beobtained. If the amount of the rubber latex (B) is less than 3% byweight, a sufficient water resistance cannot be obtained.

The solid concentration of the treating agent according to the presentinvention is suitable to be 10 to 40% by weight, preferably, 20 to 30%by weight. If the concentration is too low, the treating agent may beinsufficiently deposited on the reinforcing fiber. On the other hand, ifthe concentration is too high, it is difficult to control the amount oftreating agent deposited on the reinforcing fiber, resulting in adifficulty to provide a reinforcing fiber product with the treatingagent deposited thereon in a uniform amount.

According to the present invention, the treating agent comprises thenitrile group-containing highly saturated polymer rubber latex (A), therubber latex (B) and the RF as essential components, but if required, abase for adjusting pH, e.g., ammonia, may be incorporated into thetreating agent and further, other additives such as a stabilizer, an ageresistor and the like may be incorporated into the treating agent.

According to the present invention, the essential components of thetreating agent are coated onto a glass fiber strand by immersing a glassfiber, particularly, a strand-like glass fiber into the treating agent,removing an excessive treating agent and then, if required, drying theresulting material. In this case, greige goods, which are usuallyapplied in spinning of a glass fiber, may be either applied, or notapplied to the glass fiber strand. Then, a desired number of glass fiberstrands are collected and subjected to a twisting to provide a glassfiber cord. The glass fiber cord is embedded into an unvulcanized rubbersubstrate in a known manner and then heated and vulcanized underpressurization.

According to the present invention, the treating agent is applied to theglass fiber cord, usually in an amount of 10 to 30% by weight in termsof solids based on the glass fiber cord.

The type of the rubber to be reinforced with the glass fiber cordaccording to the present invention is particularly not limited, butillustrative of such rubbers are a chloroprene rubber, anacrylonitrile/butadiene rubber, a chlorosulfonated polyethylene rubber,a hydrogenated nitrile rubber and the like. When these rubbers are used,an extremely appropriate effect can be obtained.

When a chlorosulfonated polyethylene rubber or a hydrogenated nitrilerubber is used as a rubber to be reinforced, the glass fiber cordaccording to the present invention, preferably, is further coated withan adhesive solution containing a halogen-containing polymer such asdescribed above, an isocyanate compound, carbon black, a vulcanizingagent and the like, prior to application to such rubbers, in order tofurther enhance the adhesive property.

More specifically, according to the present invention, if the treatingagent is used as a primary coating agent, a halogen-containing polymerbased adhesive solution can be further used as a secondary coating agenton the glass fiber treated with such primary coating agent. Thehalogen-containing polymer based adhesive solution comprises a mixturecontaining an organic di-isocyanate, a chlorosulfonated polyethylene andan aromatic nitroso compound.

A secondary coating layer made by application of the secondary coatingagent can be formed by applying, for example, a solution of an organicdi-isocyanate, a chlorosulfonated polyethylene and an aromatic nitrosocompound dissolved in an organic solvent onto a glass fiber cord coatedwith a primary coating agent such as described above.

Preferred examples of the organic di-isocyanates are hexamethylenedi-isocyanate, isophoron di-isocyanate, methylene-bis-(4-cyclohexylisocyanate), toluene diisocyanate, xylene di-isocyanate, naphthalenedi-isocyanate, methylene-bis-(phenyl isocyanate) and the like. They maybe used in a combination of two or more of them. If the organicdi-isocyanates have isomers with substituent groups, as is the case withtoluene di-isocyanate and methylene-bis-(phenyl isocyanate), a mixtureof such isomers may be used. These organic di-isocyanates can be alsoused in the form with the isocyanate group protected by phenol orlactum. The organic di-isocyanate in the form protected in such a manneris advantageously used, when the secondary coating agent is used in theform of a mixture in an aqueous medium such as an aqueous emulsion.

A chlorosulfonated polyethylene having, for example, a chlorine contentof 20 to 45% by weight and a sulfonyl sulfur content of 1 to 2.5% byweight, can be usually used as the above-described chlorosulfonatedpolyethylene. Particularly, a chlorosulfonated polyethylene having, forexample, a chlorine content of 25 to 45% by weight and a sulfonyl sulfurcontent of 1.0 to 1.5% by weight, is advantageously used. In addition, apreferred chlorosulfonated polyethylene exhibits Mooney viscosity of 20to 50 ML1+4 (at 100° C.). The chlorosulfonated polyethylene is solublevery well in aromatic hydrocarbons such as benzene, toluene and xylene,and a halogenated hydrocarbons such as trichloroethylene.

The aromatic nitroso compound may be any of hydrocarbons such asbenzene, naphthalene, anthracene and biphenyl which have at least twonitroso groups directly bonded to non-adjacent carbon atoms in a ring.More specifically, such a nitroso compound is represented as an aromaticpoly-C-nitroso compound which has one or three aromatic nuclei includingcondensed aromatic nuclei and has two or six nitroso groups directlybonded to non-adjacent nucleus carbon atoms. Preferred poly-C-nitrosocompounds are aromatic di-nitroso compounds, particularly, di-nitrosobenzenes or di-nitroso naphthalenes such as aromatic meta- orpara-di-nitroso benznen or aromatic meta- or para-di-nitrosonaphthalene. The hydrogen atom in an aromatic nucleus can be substitutedby a substituent such as alkyl, alkoxy, cycloalkoxy, aryl, aryl alkyl,alkyryl, arylamines, arylnitroso, amine, halogens (fluorine, chlorine,bromine and iodine) and the like. The presence of such a substituent onthe aromatic nucleus exerts little influence to the active effect of thepoly-C-nitroso compound used in the present invention. Insofar as beingpresently known, the nature of the substituent is not limited in anyway, whether the substituent is an organic or inorganic group. It shouldbe understood that when the poly-C-nitroso benzene or poly-C-nitrosonaphthalene is referred to, it embraces both of a substituted nitrosocompound and a non-substituted nitroso compound, unless otherwisedefined.

An especially preferred poly-C-nitroso compound is a compoundrepresented by a general formula:

    (R.sub.1).sub.p --Ar--(NO).sub.2

wherein Ar is selected from a group consisting of phenylenes andnaphthalenes; R₁ is a monovalent organic radical selected from a groupconsisting of alkyl, cycloalkyl, aryl, arylalkyl, alkyryl, arylamine,alkoxy groups having 1 to 20 carbon atoms, amino group and halogens(fluorine, chlorine, bromine and iodine), and preferably, an alkyl grouphaving 1 to 6 carbon atoms; and p is 0, 1, 2, 3 or 4, preferably, 0.

Preferred partial and non-limited examples of the poly-C-nitrosocompounds suitable in carrying out the present invention arem-di-nitroso benzene, p-di-nitroso benzene, m-di-nitroso naphthalene,p-di-nitroso naphthalene, 2,5-di-nitroso-p-cymene,2-methyl-1,4-di-nitroso benzene, 2-methyl-5-chloro-1,4-di-nitrosobenzene, 2-fluoro-1,4-di-nitroso benzene, 2-methoxy-1,3-di-nitrosobenzene, 5-chloro-1,3-dinitroso benzene, 2-benzyl-1,4-di-nitrosobenzene, and 2-cyclohexyl-1,4-di-nitroso benzene.

The secondary coating agent may contain an isocyanate, achlorosulfonated polyethylene and an aromatic nitroso compound. Thesecondary coating agent further may contain, or rather desirablycontains inorganic filler or fillers. Illustrative of the inorganicfillers are carbon black, magnesium oxide, silica, lead oxides, andmagnesium carbonate. Among them, carbon black is especially preferred.

The secondary coating agent may be prepared in the form of a solution ora dispersion having a solid content of 3 to 25% by weight, morepreferably, 5 to 15% by weight. The organic di-isocyanate occupies asolid content of preferably 10 to 50%, more preferably, 25 to 45% byweight. The chlorosulfonated polyethylene occupies a solid content ofpreferably 10 to 60%, more preferably, 20 to 50% by weight. The aromaticnitroso compound occupies a solid content of preferably 1 to 20%, morepreferably, 2 to 15% by weight. The inorganic filler occupies a solidcontent of preferably at most 30%, more preferably, 5 to 20% by weight.

The secondary coating agent is applied usually in the form of a solutionor a dispersion having a solid content of 1 to 5% by weight (preferably2 to 4% by weight onto a glass fiber cord having a primary coating layerthereon, and then dried for 0.1 to 1 minute at a temperature of 80° to150° C. to provide a secondary coating layer on the primary coatinglayer of the glass fiber cord.

A rubber article produced using a glass fiber product according to thepresent invention as a reinforcing material has excellent resistances toheat, flex-fatigue and water. Therefore, the glass fiber productaccording to the present invention can be used extremely appropriatelyas a reinforcing fiber used, for example, for a timing belt, a toothedbelt, a rubber tire and the like in an automobile, which may besubjected to a flexing stress under an environment influenced by a heatand water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of a testing machine for measuring thethermal travel test performance of a toothed belt reinforced with aglass fiber product according to one embodiment of the presentinvention;

FIG. 2 is a schematic side view of a water injection travel testingmachine for measuring the thermal travel test performance of the toothedbelt reinforced with a glass fiber product according to one embodimentof the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in further detail by way ofExamples.

EXAMPLE 1

(1) Non-alkali glass filaments having a diameter of 9 μm were spinnedand collected with greige goods to provide a glass strand of 33.7 tex.The three strands were doubled to provide a glass fiber product. Atreating agent comprising a following composition was applied to theglass fiber product, so that the deposited amount were of 20% by weight,and the resulting material was subjected to a thermal treatment for 2minutes at 280° C.

    ______________________________________                                        Water-soluble resorcinol/formaldehyde                                                                  30% by weight                                        condensate (R/F = 1/1.5, a solid content                                      of 8% by weight)                                                              Vinylpyridine/butadiene/styrene terpolymer                                                             30% by weight                                        latex (Nipol 2518FS a solid content                                           of 40% by weight)                                                             Nitrile group-containing highly saturated                                                              35% by weight                                        polymer latex (Zetpole Latex 2020, an iodine                                  value of 28, a solid content of 40% by weight)                                25% ammonia water        1% by weight                                         Water                    4% by weight                                         Total                    100% by weight                                       ______________________________________                                    

Then, the glass fiber bundle was subjected to a primary twisting in a Zdirection (S direction) in 2.1 twists per 1 inch. Eleven primarilytwisted fiber bundles were doubled and subjected to a final twisting inan S direction (Z direction) in 2.1 twists per 1 inch, thereby producinga glass fiber cord of ECG 150 3/11 2.1 S(Z).

The ECG 150 3/11 2.1 S(Z) will be described below. E representsnon-alkali glass; C represents a long fiber; G means that the diameterof the filament is about 9 μm; 150 means that the strand is of 15,000yards/pound; a numerator 3 of 3/11 represents the number of strands tobe primarily twisted; a denominator 11 of 3/11 represents the number ofprimarily twisted bundles to be finally twisted; and 2.1 S (Z) meansthat eleven primarily twisted fiber bundles are doubled and subjected toa final twisting in an S direction (z direction) in 2.1 twists per 1inch.

Using this cord as a reinforcing fiber and a rubber having a formulationgiven in Table 1, a toothed belt having a width of 19 mm and a length of980 mm was fabricated.

                  TABLE 1                                                         ______________________________________                                        Rubber formulation                                                            Chemicals incorporated                                                                          Part by weight                                              ______________________________________                                        Chloroprene rubber *.sup.1)                                                                     100                                                         Magnesium oxide   4                                                           Oil *.sup.2)      15                                                          Vulcanizing accelerator *.sup.3)                                                                1.5                                                         Carbon black      60                                                          Zinc white        5                                                           Sulfur            1.0                                                         Stearic acid      2.5                                                         ______________________________________                                         *.sup.1) Neoprene GW (trade name) made by du Pond de Nemours. E. I., and      Co.                                                                           *.sup.2) Mineral oil (Naphthenic process oil)                                 *.sup.3) 2mercaptoimidazoline                                            

This toothed belt was attached to a heat-resistance travel testingmachine equipped with a driving motor of 6,000 rpm shown in FIG. 1. Itshould be noted that the toothed belt 1, which is a subject to betested, transmits a driving force of a driving pulley 2 rotativelydriven at 6,000 rpm by the driving motor (not shown) to a followerpulley 3. An idler 4 is used to adjust the degree of tension of thetoothed belt 1, and a load 5 applied to a shaft of the follower pulley 3provides a tension to the toothed belt 1.

A heat-resistance travel test was carried out for 400 hours under anenvironment at 80° C., and after the test, a tensile strength of thebelt was measured to determine a percent based on the tensile strengthbefore the test, i.e., a retention of tensile strength. Further, thetoothed belt was attached to a water injection travel testing machineequipped with a driving motor of 6,500 rpm shown in FIG. 2. It should benoted that the toothed belt 1 as a subject to be tested transmits adriving force of a driving pulley 2 rotatively driven at 6,500 rpm by adriving motor (not shown) to a follower pulley 3. An idler pulley 4 forproviding a tension to the toothed belt 1 is also used as in FIG. 1. Thetoothed belt 1 was travelled for 24 hours under an environment at roomtemperature while dropping water 6 at a rate of 1 liter/hr to a portionof a tooth face of the toothed belt 1 started to be meshed with a toothface of the follower pulley 3. After the test, a retention of tensilestrength of the belt was determined. Results are given in Table 2.

EXAMPLE 2

Using a treating agent comprising a following composition in place ofthe composition used in Example 1, a test similar to that in the Example1 was carried out to provide results given in Table 2.

    ______________________________________                                        Water-soluble resorcinol/formaldehyde                                                                  30% by weight                                        condensate (R/F = 1/1.5, a solid content                                      of 8% by weight)                                                              Vinylpyridine/butadiene/styrene terpolymer                                                             35% by weight                                        latex (Nipol 2518FS a solid content of                                        40% by weight)                                                                Nitrile group-containing highly saturated                                                              10% by weight                                        polymer latex (Zetpole Latex 2020, a solid                                    content of 40% by weight)                                                     Chlorosulfonated polyethylene latex                                                                    20% by weight                                        (Esprene 200, a solid content of 40% by weight)                               25% ammonia water        1% by weight                                         Water                    4% by weight                                         Total                    100% by weight                                       ______________________________________                                    

COMPARATIVE EXAMPLE 1

Using a treating agent comprising a following composition in place ofthe composition used in Example 1, a test similar to that in the Example1 was carried out to provide results given in Table 2.

    ______________________________________                                        Water-soluble resorcinol/formaldehyde                                                                  30% by weight                                        condensate (R/F = 1/1.5, a solid content                                      of 8% by weight)                                                              Vinylpyridine/butadiene/styrene terpolymer                                                             30% by weight                                        latex (Nipol 2518FS a solid content of                                        40% by weight)                                                                Dicarboxylated butadiene/styrene copolymer                                                             15% by weight                                        latex (Nipol 2570X5 a solid content of                                        40% by weight)                                                                Chlorosulfonated polyethylene latex                                                                    20% by weight                                        (Esprene 200, a solid content of                                              40% by weight)                                                                25% ammonia water        1% by weight                                         Water                    4% by weight                                         Total                    100% by weight                                       ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Results of the test for the belt                                                             Example Com. Example                                                         1     2      1                                                  ______________________________________                                        Retention (%) of tensile                                                                      81      78     72                                             strength of the belt after the                                                heat-resistance travel test                                                   Retention (%) of tensile                                                                      64      67     51                                             strength of the belt after the                                                water injection travel test                                                   ______________________________________                                         Com. = Comparative                                                       

EXAMPLE 3

The glass fiber cord produced in Example 1 was further coated with ahalogen-containing polymer based adhesive solution (which comprisesKemlock 402 (trade name, made by Load Corporation, and a solid contentof 14.5%) diluted by toluene), so that the deposited amount was of 3.5%by weight based on the glass fiber cord, and then, the resulting cordwas dried. Using this coated glass fiber cord as a reinforcing fiber anda rubber having a formulation given in Table 3, a toothed belt wasfabricated, and subjected to a travel test in the same manner as inExample 1, but the heat-resistance travel test temperature was changedfrom 80° C. to 100° C., Results are given in Table 4.

                  TABLE 3                                                         ______________________________________                                        Rubber formulation                                                            Chemicals incorporated  Part by weight                                        ______________________________________                                        Hydrogenated nitrile rubber                                                                           100                                                   (Zetpole 2020)                                                                Carbon black            40                                                    Zinc oxide              5                                                     Stearic acid            1                                                     Thiokol TP-95 *.sup.1)  5                                                     Sulfur                  0.5                                                   Tetramethyl thiuram disulfide                                                                         1.5                                                   Cyclohexylbenzothiazy sulfenamide                                                                     1.0                                                   ______________________________________                                         *.sup.1) A trade name of a high molecular type polyester based plasticize     made by Toray Industries, Inc.                                           

EXAMPLE 4

Using the glass fiber cord produced in Example 2, a toothed belt wasfabricated in the same manner as in Example 3, and subjected to a traveltest in the same manner as in Example 3. Results are given in Table 4.

EXAMPLE 5

Using a secondary coating treating solution having a followingcomposition:

    ______________________________________                                        Methylene-bis-(4-phenyl isocyanate)                                                                  4.5 part by weight                                     Chlorosulfonated polyethylene                                                                        5.25 part by weight                                    (made under a trade name of TS-340 by                                         Toyo Soda, Co., Corp., and having a                                           chlorine content of 43% by weight, a                                          sulfur content of 1.1% by weight and                                          Mooney viscosity of 30 (ML1 + 4                                               (at 100° C.)                                                           p-Dinitrosobenzene     2.25 part by weight                                    Carbon black           3.0 part by weight                                     Mixed solvent of xylene and trichloro-                                                               85.0 part by weight                                    ethylene (ratio of xylene to                                                  trichloroethylene = 1.5/1.0)                                                  Total                  100 part by weight                                     ______________________________________                                    

the glass fiber cord produced in Example 2 was coated therewith, so thatthe deposited amount (of solids) was of 3.5 by weight based on the glassfiber cord, and the resulting cord was then dried. Using this glassfiber cord as a reinforcing fiber and a rubber having the sameformulation as in Table 3, a toothed belt was fabricated and subjectedto a travel test, in the same manner as in Example 1, but theheat-resistance travel test temperature was changed from 80° C. to 100°C. Results are given in Table 4.

COMPARATIVE EXAMPLE 2

Using the glass fiber cord produced in Comparative Example 1, a toothedbelt was fabricated in the same manner as in Example 3, and subjected toa travel test in the same manner as in Example 3. Results are given inTable 4.

COMPARATIVE EXAMPLE 3

Using a treating agent comprising a following composition:

    ______________________________________                                        Water-soluble resorcinol/formaldehyde con-                                                            30% by weight                                         densate (R/F = 1/1.5, a solid content of                                      8% by weight)                                                                 Nitrile-containing highly saturated polymer                                                           60% by weight                                         latex (Zetpole Latex 2020, a solid content                                    of 40% by weight)                                                             25% ammonia water       1% by weight                                          Water                   9% by weight                                          Total                   100% by weight                                        ______________________________________                                    

in place of the composition used in Example 1, a glass fiber cord wasfabricated in the same manner as in Example 1. Using this glass fibercord, a toothed belt was fabricated in the same manner as in Example 3,and subjected to a travel test in the same manner as in Example 3.Results are given in Table 4.

                  TABLE 4                                                         ______________________________________                                        Results of the test for the belt                                                            Example   Com. Example                                                        3    4     5      2     3                                       ______________________________________                                        Retention (%) of tensile                                                                      95     93    95   78    93                                    strength of the belt after the                                                heat-resistance travel test                                                   Retention (%) of tensile                                                                      73     85    87   62    62                                    strength of the belt after the                                                water injection travel test                                                   ______________________________________                                    

INDUSTRIAL APPLICABILITY

If the glass fiber product coated with the coating composition accordingto the present invention is used for reinforcing a rubber article suchas a belt, a tire and the like, the reinforced rubber article has highheat- and water-resistances, and even if the reinforced rubber articleis repeatedly subjected to a flexing stress under an environment of ahigh temperature and a high humidity, it is less reduced in strength andexhibits an excellent performance.

What is claimed is:
 1. A coated glass fiber for reinforcing a rubber,said coated glass fiber comprising:a glass fiber substrate; a firstcoating covering said glass fiber and formed from a first coatingcomposition comprising, based on total solids within said first coatingcomposition:15-80 wt. % of a nitrile group-containing, highly saturatedpolymer rubber latex (A) having an iodine value of 120 or less; 5-70 wt.% of a rubber latex (B) other than said rubber latex (A); and 2-15 wt. %of a water-soluble resorcinol/formaldehyde condensate; and a secondcoating covering said first coating and formed from a second coatingcomposition comprising, based on total solids within said second coatingcomposition:10-50 wt. % of an isocyanate; 10-60 wt. % of achlorosulfonated polyethylene; and 1-20 wt. % of an aromatic nitrocompound.
 2. A coated glass fiber according to claim 1, wherein saidsecond coating composition additionally comprises 1-20 wt. % of at leastone inorganic filler.
 3. A coated glass fiber according to claim 1,wherein said rubber latex (B) is at least one member selected from thegroup consisting of a butadiene/styrene copolymer latex, adicarboxylated butadiene/styrene copolymer latex, avinylpyridine/butadiene/styrene terpolymer latex, a chlorosulfonatedpolyethylene latex, and an acrylonitrile/butadiene copolymer latex.
 4. Acoated glass fiber according to claim 1, wherein said rubber latex (B)is a mixture of a vinylpyridine/butadiene/styrene terpolymer latex and achlorosulfonated polyethylene latex.
 5. A process for coating a glassfiber substrate to produce a coated glass fiber for reinforcing arubber, said process comprising:coating the glass fiber substrate with afirst coating composition to form a first coating, said first coatingcomposition comprising, based on total solids within said first coatingcomposition:15-80 wt. % of a nitrile group-containing, highly saturatedpolymer rubber latex (A) having an iodine value of 120 or less; 5-70 wt.% of a rubber latex (B) other than said rubber latex (A); and 2-15 wt. %of a water-soluble resorcinol/formaldehyde condensate; and coating saidfirst coating with a second coating composition to form a secondcoating, said second coating composition comprising, based on totalsolids within said second coating composition:1- 50wt. % of anisocyanate; 10-60 wt. % of a chlorosulfonated polyethylene; and 1-20 wt.% of an aromatic nitro compound.
 6. A process for coating a glass fibersubstrate according to claim 5, wherein said second coating compositionfurther comprises 1-20 wt. % of at least one inorganic filler.
 7. Aprocess for coating a glass fiber substrate according to claim 5,wherein said rubber latex (B) is at least one member selected from thegroup consisting of a butadiene/styrene copolymer latex, adicarboxylated butadiene/styrene copolymer latex, avinylpyridine/butadiene/styrene terpolymer latex, a chlorosulfonatedpolyethylene latex, and an acrylonitrile/butadiene copolymer latex.
 8. Aprocess for coating a glass fiber substrate according to claim 5,wherein said rubber latex (B) is a mixture of avinylpyridine/butadiene/styrene terpolymer latex and a chlorosulfonatedpolyethylene latex.
 9. A process for coating a glass fiber substrateaccording to claim 5 further comprising drying said first coatingcomposition and drying said second coating composition.